Method of producing an end ring for alpha rotor



March 27, 1934. 1 H LELAND AL 1,952,266

METHOD OF PRODUCING AN END RING FOR A ROTOR Filed 001:. 21. 1932 /N VE N 7 0515.

' GEO/F65 hf LELAN W/LL/AM L. OER/E N.

fhe/r ATTORNE Y Patented Mar. 27, 1934 Fries METHOD OF PRODUCING AN END RING FOR A ROTOR George H. Leland and William L. OBricn, Day-' ton, Ohio, assignors of one-fourth to said Leland and three-fourths to The Leland Electric Company, Dayton, .Ohio, a corporation of Ohio Application October 21, 1932, Serial No. 638,874

9 Claims.

This invention relates to a method of producing an end ring for a rotor.v

Rotors of the squirrel cage type are usually provided at each end with a ring of conducting material, such as copper, and the two rings are connected by rods or long rivets of conducting material. The stamping of these end rings from sheet metal involves a large waste of material and various expedients have been adapted for avoiding this waste but the rings, for the most part at least, have not been entirely satisfactory, due either to the character of the ring or to the cost of producing the same.

One object of the present invention is to provide a simple and eflicient method whereby a sati factory end ring may be produced at a low cost.

A further object of the invention is to provide a method of forming an end ring from wire.

' Other objects of the invention will appear as the method and ring are described in detail.

- In the accompanying drawing Fig; 1 is a plan view of a portion of the severing device, showing a coil of wire thereon; Fig. 2 is an edge view of a winding which has been severed from the coil; Fig. 3 is an edge view of the winding with the edge portions in overlapping engagement; Fig. 4 is a sectional detail view of a portion of a press for flattening the winding or ring, showing the same at the beginning of the flattening operation; Fig. '5 is a similar View showing the same at the end of the flattening operation; Fig. 6 is a sectional detail view of the flattened ring; Fig. 7 is a face View of the flattened ring; Fig. 8 is a face view of the finished ring showing the series of perforations therein; Fig. 9 is a perspective view of a rotor showing the end rings applied thereto; and Fig. 10 is a section taken on the line 10l0 of Fig. 9.

In the drawing wehave illustrated the preferred form of end ring and one method of producing the same. It will be understoodhowever, that the ring may take various shapes and that the method of producing the same may be varied.

In producing the end ring a section oi wire or thin rod is formed into annular shape with its ends overlapping and is then subjected to pressure in the direction of its axis to impart thereto the desired cross sectional shape. It is then provifcled with the circumferential series of openings .to receive the connecting rods or rivets. Preferably the rings are formed from copper wire, which is one of the least expensive forms in which copper can be purchased, but it will be understood that the ring may be formed of any suitable material and the thickness of the wire will be determined according tothe cross sectional dimensions of the finished end ring.

According to the particular method here illustrated the wire is first wound into a cylindrical coil and the windings of that coil are successively severed one from the other to provide individual rings; ihe line of severance extends obliquely to the length of the winding so that the end portions of each severed winding or ring will overlap and will be of a combined thickness substantially equal to the thickness ofv the wire. While the line of severance'should extend in a generally oblique direction it may take various shapes and, as here illustrated, it has an intermediate portion which extends substantially parallel with the plane of the severed winding and the. end portions of the line of severance curve sharply outwardly to the respective sides of the winding. Consequently the ends of each severed winding will not only overlap but will have abutting engagement which will tend tomaintain the same in their proper relation.

The successive windings may be severed one from the other in any suitable manner but this is preferably accomplished by a suitable punch and die. In Fig. 1 the coil is shown at 11 and as illustrated it is tightly wound with the successive windings in engagement one with the other. This coil is supported on a die 12, which extends into the same, and the innermost winding 13 abuts againsta shoulder 14 on the die. The die has a recess 15 arranged beneath the coil at the end of the innermost winding, that is, be-- neath the line of severance, and is provided with a cutting. edge 16 with which, cooperates a suitable punch,.not shown, to sever the two windings along an oblique line. The particular construction of the punch and die forms no part of the present invention and need not be fully illustrated. It may be noted, however, that the punch has a part fitting in the recess 15 against which the free end of-the innermost winding l3, which has been previously formed, bears in such a manner as to properly position the coil with relation'to the punch. The operation of the punch and die will sever this imiermost winding from the second winding along an oblique line and the severed'winding will be of a total length greater than the circumference of the coil, so that the end portions thereof may overlap, the severed winding having at the end of vthe cutting operation the shape shown in Fig. 2. When this winding is removed from the die the resiliency of the metal will tend to move the overlapping ends into engagement as shown in Fig. 3, thereby forming closed rings having the cross sectional shape of the wire from which it was formed. In the present instance, a round wire has been shown but obviously the wire may be of any desired cross sectional shape.

The initial ring thus formed is then subjected. to pressure to impart thereto the desired cross sectional shape for the finished ring. This is preferably accomplished by inserting the same in a suitable press, such as a coining press. In Figs. 4 and 5 we have shown portions of the die members forming part of this press, the lower or stationary die member being shown at 18 and the movable die member at 19. The lower die member is shown as having a shallow annular recess 20 adapted to receive the ring 13 and to limit the lateral expansion thereof as it is flattened by the action of the upper die member 19, thus preventing the distortion of the ring and imparting thereto the desired cross sectional shape. In the present instance, the inner and outer walls of the recess are parallel so that the inner and outer edges of the flattened ring will be concentric, as shown in Figs. 6 and '7. While the upper and lower sides of the flattened ring are here shown as flat and parallel it will be apparent that these surfaces may have any suitable shape.

The contacting surfaces of the relatively long overlapping end portions of the winding which forms the initial ring are of such shape that they will have little or no tendency to slip one upon the other when pressure is applied to the ring. Consequently these contacting surfaces will be pressed into tight engagement one with the other and their surfaces will be exactly complementary, thereby providing firm electrical contact throughout the area of the contacting surfaces, which will offer no appreciable resistance to the flow of current through the joint. When the flattened ring is removed from the coining press the overlapping ends adhere tightly one to the other and will not separate in the handling of the ring. When the ring is mounted on the rotor the rods or rivets extend through the overlapping portions and serve to prevent any separation of the joint in service. If desired, the joint may be further strengthened, after it is applied to the rotor.

After the flattened ring has been removed from the press it is provided with a circumferential series of openings 21, as shown in Fig. 8, these openings being preferably formed therein by subjecting the ring to the action of a suitable punch and die. The forming of the openings in the flattened ring completes the formation thereof and two of the rings so formed are then applied to a rotor, as shown at 22 in Figs. 9 and 10, and the two rings connected one to the other by long rivets 23 in the usual manner.

While we have described one method of producing the ring and have shown one form of ring produced by that method we wish it to be understood that we do not desire to be limited to the details of the method or of the shape of the ring as various modifications in either may occur to a person skilled in the art.

Having now fully described our invention, what We claim as new and desire to secure by Letters Patent, is:

1. The method of producing an end ring for a rotor which comprises forming a section of wire into a ring with the end portions of said section overlapping, subjecting said ring to pressure in the direction of its axis to reduce the thickness thereof and increase the width thereof in cross section, and providing said ring with a circumferential series of openings.

2. The method of producing an end ring for a rotor which comprises forming a section of wire into a ring, cutting away the adjacent sides of the end portions of said wire and arranging said end portions in overlapping relation, subjecting the ring so formed to pressure in the direction of its axis to impart thereto the desired cross sectional shape and then forming a circumferential series of openings in the ring.

3. The method of producing an end ring for a rotor which comprises forming a section of wire into a ring with the end portions of said wire overlapping, subjecting said ring to the action of a press, one member of which has a shallow annular recess to receive said ring and determine the shape thereof as it is flattened by said press, and then forming a circumferential series of openings in said flattened ring.

4. The method of producing an end ring for a rotor which comprises winding a wire into a coil, severing each successive winding along a line oblique to the length of the wire to form a ring, the line of severance being so arranged that the ends of said winding will overlap, then subjecting each ring to the action of a press, one member of which has a shallow annular recess to receive the ring and limit the lateral expansion of the same when it is flattened by the press, and then punching a circumferential series of holes in the flattened ring.

5. The method of forming an end ring for a rotor which comprises winding a wire into a coil, severing each successive winding along a line oblique to the length of the wire to form a ring, the line of severance being so arranged that the end portions of the winding will overlap, and then subjecting each ring to pressure in the direction of its axis to flatten the same, and forming a circumferential series of openings in the flattened ring.

6. The method of producing an end ring for a rotor, having uniform conductivity throughout its length, which comprises forming a section of wire into a ring, said section having a length greater than the circumference of the ring, cutting away the adjacent sides of the end portions of said wire at a sharp angle to the length of the wire to provide the same with relatively long overlapping end portions, subjecting the ring so formed to pressure in the direction of its axis to flatten the same and to press the opposed surfaces of said overlapping portions into tight electrical contact throughout their area, and forming a series of openings in the flattened ring, a part of said openings being formed in said overlapping portions.

7. The method of forming a ring for a rotor, having uniform conductivity throughout its length, which comprises winding a wire into a coil, severing each successive winding along a line which extends entirely across the winding at a sharp angle to the length of the wire to provide the severed winding with relatively long overlapping end portions, the combined thickness of which is substantially equal to the thickness of the wire, subjecting each severed winding to pressure in the direction of its axis to flatten the same and to press the opposed sur- 7 faces of said overlapping portions into firm electrical contact throughout their area, and then forming a circumferential series of rivet openings in the flattened ring, a part of said openings being formed in said overlapping portions.

8. The method of forming an end ring for a rotor, having uniform conductivity throughout its length, which comprises winding a wire into a coil, successively severing the individual windings of said coil along a line which extends entirely across the winding at a sharp angle to the length of the Wire to form a split ring having relatively long overlapping end portions, the combined thickness of said end portions being substantially equal to the thickness of said wire, and subjecting each split ring so formed to pressure in the direction of its axis to flatten the same and to press the opposed surfaces of said overlapping portions into firm electrical contact throughout their area.

9. The method of producing an end ring for a rotor, having uniform conductivity throughout its length, which comprises winding a wire into a coil, successively severing the individual windings of said coil along an oblique line extending entirely across the same at a sharp angle to form a split ring having relatively long overlapping end portions, the line of severance having an intermediate portion extending substantially parallel with the plane of the ring and spaced substantially equal distances from the respective faces of the ring and having end portions extending at obtuse angles to said intermediate portion, whereby the overlapping end portions of each winding will have a combined thickness GEORGE H. LELAND. WILLIAM L. O'BRIEN. 

